Cover body of airbag device

Abstract

To provide a cover body of an airbag device that enables an airbag to expand properly.SOLUTION: A cover body 13 of an airbag device comprises a cover main body part 15 that covers an airbag 11 in a folded-back state and a decorative body 16 mounted on the cover main body part 15. The decorative body 16 is at a position opposing to an expansion center P of the airbag 11. The cover main body part 15 has: a part 28 to be fractured which comprises a fracture start-point part 33 arranged at a position deviated with respect to the expansion center P of the airbag 11 and is formed at a rear side of an opposing part 23, which is cleaved by expansion pressure of the airbag 11 when the airbag 11 inflates and expands to section the opposing part 23 into a plurality of door portions 29; and a protruding part 39 that comes close to a position corresponding to an outer edge part of the decorative body 16 and to the fracture start-point part 33 and protrudes most toward the airbag 11, on the rear side of the opposing part 23.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cover body for an airbag device in which a decorative body is attached to a cover main body that covers a stored airbag. [Background technology]

[0002] Conventionally, the cover body of an airbag device attached to a steering wheel, which is the handle of a vehicle such as an automobile, has a planned rupture portion on the back side facing the airbag, and is configured to tear from the planned rupture portion due to the pressure of the airbag inflated by gas supplied from an inflator, opening an ejection port that allows the airbag to protrude toward the occupant.

[0003] Among such covers for airbag devices, those with a decorative element in the center are known. In this configuration, the breakable portion is set around the decorative element, and the breakable portion's break start point is offset from the center of deployment of the airbag (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-159655 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-described configuration, the initial stress caused by the inflation pressure of the airbag is less likely to be transmitted to the rupture initiation portion, so it is necessary to rupture the intended rupture portion more quickly and stably to stabilize the deployment behavior of the airbag.

[0006] SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide a cover body for an airbag device that can deploy an airbag in a satisfactory manner. [Means for solving the problem]

[0007] A cover body of an airbag device according to one aspect of the present invention comprises a cover main body portion that covers the airbag in a folded state, and a decorative body attached to the cover main body portion, wherein the decorative body is located opposite the center of deployment of the airbag, and the cover main body portion has an opposing portion that faces the airbag and where the decorative body is located on the front side, a planned rupture portion that is formed on the back side of the opposing portion and has a rupture origin portion that is located in a position offset from the center of deployment of the airbag, and that ruptures due to the deployment pressure of the airbag when the airbag is inflated and deployed, thereby dividing the opposing portion into multiple door portions, and a protrusion on the back side of the opposing portion that is close to a position corresponding to the outer edge of the decorative body and the rupture origin portion and protrudes the most toward the airbag. [Effects of the Invention]

[0008] According to the present invention, the airbag can be deployed satisfactorily. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a vertical cross-sectional view showing a cover body of an airbag device according to an embodiment of the present invention. [Figure 2] 3A is a longitudinal sectional view showing an enlarged portion of the cover body, and FIG. 3B is a perspective view showing an enlarged portion of the cover body. [Figure 3] FIG. [Figure 4] FIG. 2 is a front view showing an example of a steering wheel equipped with the same airbag device. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] In FIG. 4, reference numeral 1 denotes a steering wheel (steering wheel) for steering a vehicle such as an automobile. In this embodiment, the steering wheel 1 is exemplified as a steering wheel having a central boss 2 surrounded by a rim (grip) 3, which is a circular or arc-shaped handle, and the boss 2 and rim 3 connected by radial spokes 4. However, the steering wheel 1 is not limited to this, and may be a control stick type, such as a so-called yoke type. The steering wheel 1 is a steering shaft, which is a steering shaft that is usually installed in a vehicle in an inclined state, with the boss 2 attached to the steering shaft. Hereinafter, up, down, left, and right directions will be described based on the direction as seen by a passenger seated in the driver's seat, with the passenger side being the front side or rear side and the steering shaft side being the back side or front side. In the figure, the arrow U direction is the upward direction, the arrow D direction is the downward direction, the arrow FR direction is the forward direction, the arrow RR direction is the rearward direction, the arrow L direction is the leftward direction, and the arrow R direction is the rightward direction. Furthermore, the positions and shapes of the various parts of the steering wheel 1 will be described based on the steering reference state shown in FIG. 4, that is, the neutral position.

[0012] The steering wheel 1 is equipped with a driver's seat airbag (DAB) device 6, which is a module that forms the front side of the boss portion 2. The airbag device 6 is also called an airbag module. As shown in FIG. 1, the airbag device 6 is configured such that a folded bag-shaped airbag 11, an inflator 12 that injects gas, and the like are attached to a case body 10 that serves as an attachment member, and the airbag 11 and the inflator 12 are covered by a cover body 13.

[0013] Case body 10, also called a base plate, is attached to the core of steering wheel 1 (shown in FIG. 4). In this embodiment, case body 10 also serves as a horn plate for the horn device, and is elastically attached to the core of steering wheel 1 (shown in FIG. 4) via a damper while being biased forward. When airbag device 6 is pushed backward against the bias of the damper, contacts on the case body 10 and contacts on the core come into contact and establish electrical continuity, thereby closing the circuit of the horn device and causing the horn device to sound. A hook-shaped locking portion is provided on the outer side of case body 10 to lock case body 10 to cover body 13.

[0014] The airbag 11 is formed in a bag shape using one or more base fabrics so that when deployed, it assumes a circular shape in front of the occupant to be protected. The airbag 11 is basically attached at a position where the center of the deployed state when viewed from the front or back coincides or nearly coincides with the centers of the case body 10 and the cover body 13. When folded, the airbag 11 protrudes rearward, closer to the cover body 13 than the case body 10. The folded shape of the airbag 11 may be set arbitrarily.

[0015] The inflator 12 is attached to the case body 10 together with the airbag 11 via an attachment member such as a retainer, with the nozzle for injecting gas inserted into the airbag 11. The inflator 12 is electrically connected to a control means such as an on-board control unit (ECU), and is arranged to inject gas into the airbag 11 in response to a signal from the control means when necessary, such as when the vehicle crashes.

[0016] 1 to 3 is also called a pad or a module cover. The cover 13 includes, for example, a cover main body 15, which is the mounting portion, and a decorative body 16 attached to the cover main body 15.

[0017] The cover main body 15 is formed, for example, from a synthetic resin. The cover main body 15 includes a front panel 20 as a covering that forms the design part of the airbag device 6, and a peripheral panel 21 that is a peripheral wall that protrudes from the rear (back surface) of the front panel 20 in a cylindrical shape, such as a generally rectangular cylindrical shape when viewed from the front. The area surrounded by the front panel 20 and the peripheral panel 21 is the airbag storage compartment in which the folded airbag 11 is stored. The portion of the front panel 20 that faces the airbag 11, i.e., the front side of the airbag storage compartment, is a facing portion 23 that is an ornament attachment portion, and the remaining portion is a non-facing portion 24. In other words, the facing portion 23 is a central region of the front panel 20 that is inside the peripheral panel 21, and the non-facing portion 24 is a peripheral region of the front panel 20 that is outside the peripheral panel 21. In this embodiment, the top panel 20 is exemplified as having a hexagonal shape when viewed from the front or back, with the left-right dimension of the upper part being shorter than the left-right dimension of the lower part, but is not limited to this and any shape may be used depending on the desired design. Also, at least a portion of the surface of the top panel 20 may be covered with a skin.

[0018] In this embodiment, the facing portion 23 is curved to bulge, for example, toward the front side (occupant side), which is the side opposite the airbag 11. In the illustrated example, the facing portion 23 bulges most toward the front at its vertical center, with its upper and lower portions curved toward the rear. In this embodiment, a linear portion 26, known as a character line, is formed on the design surface of the facing portion 23, extending in the left-right direction, at a position lower than the vertical center. The linear portion 26 is a continuous portion near the apex of a shape convex toward the front side of the surface of the facing portion 23, and the planar direction or the normal direction of the surface of the facing portion 23 changes discontinuously at the top and bottom of this linear portion 26. In other words, the angle of the tangent plane is different at the top and bottom of the surface of the facing portion 23, with the linear portion 26 as a boundary.

[0019] Additionally, a breakable portion 28 is formed on the back side of the facing portion 23, facing the airbag storage compartment. The breakable portion 28 is also called a tear line. When the facing portion 23 tears apart from the breakable portion 28, the facing portion 23 is divided into multiple door portions 29, thereby opening an outlet 30 for the airbag 11. The breakable portion 28 is formed by recessing the back side of the facing portion 23 in the shape of a narrow groove, and is weaker than the other portions of the facing portion 23. A reinforcing rib 31 may be formed at the bottom of the groove of the breakable portion 28. The breakable portion 28 may be positioned to avoid the decorative body 16 depending on the shape and number of door portions 29 to be configured. In this embodiment, as shown in FIG. 3 , the breakable portion 28 is formed in a roughly H-shape when viewed from the front or back, having side portions 32 located along both sides of the facing portion 23 and a breakable origin portion 33, which is a central portion connected between the side portions 32.

[0020] The planned side portion 32 is formed linearly along the outer shape of the side edge portion of the facing portion 23. The planned side portion 32 extends from near the upper end to near the lower end of the facing portion 23. The lower end side of the planned side portion 32 extends below the linear portion 26 when viewed from the front or rear. At least one end of the planned side portion 32, the upper end in this embodiment, is a folded portion that is curved back toward the center in the left-right direction.

[0021] The fracture origin 33 is a portion that serves as a tearing origin of the fracture portion 28. The fracture origin 33 is formed in a linear shape extending in the left-right direction. As shown in FIGS. 1 and 3 , the fracture origin 33 is located at a position offset from the deployment center P of the airbag 11. Here, the deployment center P of the airbag 11 is a position corresponding to the center of the airbag 11 in the folded state in the vertical and horizontal directions, and is located at a position corresponding to the center of the facing portion 23 in the vertical and horizontal directions. In other words, the fracture origin 33 is located at a position that does not pass through the center, i.e., the center, of the facing portion 23 in the vertical and horizontal directions when viewed from the front or rear. In this embodiment, the fracture origin 33 is located toward the bottom of the facing portion 23 in the vertical direction, and in the illustrated example, overlaps with a position corresponding to the linear portion 26 when viewed from the front or rear. 1, the intended breaking portion 28 is set so that the door portion 29 is configured to have two leaflets configured as a double-hinged door: an upper leaflet portion having a relatively large area that extends upward with the fracture origin portion 33 at its tip and hinged between the upper ends of the intended side portions 32 in the facing portion 23; and a lower leaflet portion having a relatively small area that extends downward with the hinged between the lower ends of the intended side portions 32 in the facing portion 23. However, the intended breaking portion 28 may be set so that one leaflet 29 in the facing portion 23 is formed as a single-hinged door, or so that the facing portion 23 is divided into three or more leaflets 29. Furthermore, the fracture origin portion 33 may be set so that the door portion 29 opens in any direction, such as up and down, left and right, or diagonally.

[0022] Preferably, the facing portion 23 has an opening 35 for attaching the decorative body 16. The opening 35 is covered by the attached decorative body 16 and is not exposed to the front side of the cover body 13. The opening 35 is formed in the shape of a long, thin slit or a circle, and penetrates the facing portion 23 in the front-to-back direction, which is the thickness direction. Any number of openings 35 may be set in any suitable position depending on the shape of the decorative body 16, as long as the decorative body 16 can be fixed in a balanced manner in the vertical and horizontal directions.

[0023] Preferably, the opening 35 is formed at the bottom of a receiving portion 37, which serves as a storage portion recessed into the surface of the facing portion 23. In other words, the receiving portion 37 is recessed from the front side to the back side of the facing portion 23. The receiving portion 37 is disposed, for example, in the center of the facing portion 23 in the vertical and horizontal directions. The receiving portion 37 has a shape that follows the outer shape of the decorative body 16, for example, so that the decorative body 16 can be fitted into it.

[0024] 1, 2(a), and 2(b), a protrusion 39 is formed on the back side of the facing portion 23, facing the airbag storage section. The protrusion 39 is located on the back side of the facing portion 23 at a position corresponding to the outer edge of the decorative body 16 and close to the fracture origin 33. In other words, the protrusion 39 is located at a position offset from the deployment center P of the airbag 11 when viewed from the front or back. The protrusion 39 is also located in the center in the left-right direction on the back side of the facing portion 23.

[0025] Preferably, the protrusions 39 extend or are aligned along at least a portion of the outer edge of the decorative body 16. Also, preferably, the protrusions 39 extend or are aligned along at least a portion of the fracture origin 33. In this embodiment, the protrusions 39 are formed in a rib shape. In the example shown, the protrusions 39 have a plurality of first protrusions 40 aligned along positions corresponding to the outer edge of the decorative body 16, and a second protrusion 41 extending along the fracture origin 33.

[0026] The base end of each first protrusion 40 is connected to the back side of the facing portion 23. Each first protrusion 40 is formed with a thickness in the left-right direction and is positioned at equal or approximately equal intervals from one another in the left-right direction. In this embodiment, three first protrusions 40 are set on the left and right, lined up along a position corresponding to the lower edge of the decorative body 16. In this embodiment, the first protrusions 40 extend downward from the receiving portion 37 toward the fracture origin 33. In other words, the first protrusions 40 are formed in connection with the receiving portion 37 and the second protrusions 41. In the illustrated example, the upper end of the first protrusion 40 is located close to or connected to the outer frame portion 43, which surrounds the outer edge of the opening 35 and rises behind the facing portion 23. Furthermore, the first protrusions 40 are formed so that the amount of protrusion from the back side of the facing portion 23 increases from the upper end toward the receiving portion 37, i.e., the outer edge of the decorative body 16, toward the lower end.

[0027] The second protrusions 41 are connected between the lower ends of the first protrusions 40. The second protrusions 41 are formed to have a thickness in the up-down direction and extend linearly in the left-right direction along the upper edge of the fracture origin portion 33. In this embodiment, the second protrusions 41 are formed with a left-right dimension that is equal to or smaller than the lower end of the receiving portion 37. Therefore, the second protrusions 41 are rib-shaped and short in the left-right direction. The second protrusions 41 are also formed with a thickness equal to or approximately equal to that of the first protrusions 40. The tip of the second protrusion 41 is located at a position equal to or approximately equal to the tip of the lower end side, which is the maximum protrusion position of the first protrusions 40, relative to the back surface of the opposing portion 23.

[0028] The protruding portion 39 is the portion on the back side of the facing portion 23 that protrudes most toward the airbag 11. The tip of the protruding portion 39 is located closest to the airbag 11 in the front-to-rear direction in the structure of the back side of the facing portion 23. In this embodiment, the portion of the protruding portion 39 that extends from the lower end of the tip of the first protruding portion 40 to the tip of the second protruding portion 41 protrudes by 3.7 mm or more from other portions on the back side of the facing portion 23, for example, from the back side of the receiving portion 37 that is closest to the airbag 11 in the front-to-rear direction. Note that "protruding most toward the airbag 11" means that, in the range of the back side of the facing portion 23 that faces the airbag 11 in the front-to-rear direction, there is no other portion that is closer to the airbag 11 in the front-to-rear direction than the tip of the protruding portion 39, and does not necessarily mean that the protruding amount from the back side of the facing portion 23 is the greatest. In other words, the back surface of the opposing portion 23 has various unevenness and slopes, and the back surface of the opposing portion 23 itself may be curved, so the amount of protrusion of the opposing portion 23 from the back surface is not necessarily directly related to whether or not its tip is close to the airbag 11.

[0029] The peripheral plate portion 21 is provided with a plurality of locking openings 45 which are cover body locking portions onto which the locking portions of the case body 10 are hooked.

[0030] The decorative body 16 shown in FIG. 1 is also referred to as an emblem or ornament. The decorative body 16 is composed of one or more members formed, for example, from synthetic resin, metal, or a combination thereof. In this embodiment, the decorative body 16 is composed of a single plate-shaped member with one or more mounting portions 47 protruding from the back side. The mounting portions 47 are pin-shaped, rib-shaped, or the like. The mounting portions 47 are inserted into the opening 35 of the cover main body 15 from the front side to the back side and fixed to the back side of the facing portion 23 of the cover main body 15 by welding or the like, thereby preventing the decorative body 16 from slipping off the cover main body 15. Alternatively, the decorative body 16 may be attached by multiple members that sandwich the facing portion 23 of the cover main body 15 from the front and back sides.

[0031] In this embodiment, the decorative body 16 is fitted into the receiving portion 37 and is located at the center in the vertical and horizontal directions on the front side of the facing portion 23 of the cover main body 15. In other words, the decorative body 16 is located at the center of the facing portion 23. Therefore, when viewed from the front, the decorative body 16 is located in a range that includes a position facing the deployment center P of the airbag 11 in the front-to-rear direction. In the example shown, the decorative body 16 protrudes toward the front side relative to the design surface of the facing portion 23 of the cover main body 15, but this is not limiting, and the decorative body 16 may be flush with the design surface of the facing portion 23 or may be recessed relative to the design surface of the facing portion 23.

[0032] The shape of the decorative body 16 may be set arbitrarily, but in this embodiment, for example, it has a shape with a longitudinal direction in the vertical direction, and in the example shown, it is an ellipse with a major axis in the vertical direction and a minor axis in the horizontal direction. In this embodiment, the decorative body 16 has a shape in which the left-right dimension is smallest at both the top and bottom ends and largest at the center in the vertical direction.

[0033] When manufacturing the airbag device 6, the inflator 12 is attached to the folded airbag 11, and the airbag 11 together with the inflator 12 is assembled to the case body 10 via a retainer, and then the locking portion of the case body 10 is hooked onto the locking opening 45 of the cover body 13, which has the decorative body 16 assembled and fixed to the cover main body 15, to assemble the airbag device 6.

[0034] When a vehicle having an airbag device 6 with a cover body 13 attached to a steering wheel 1 collides, the control means outputs a signal to activate the inflator 12, which supplies gas to the airbag 11, causing the airbag 11 to rapidly inflate. At this time, because the protruding portion 39 protrudes most from the rear side of the facing portion 23 of the cover body 13 that faces the airbag 11, the inflated airbag 11 hits the protruding portion 39 first, as shown in FIG. 1, and the initial stress due to the inflation pressure of the airbag 11 is concentrated on the protruding portion 39. Because the protrusion 39 is close to the fracture origin 33 and the second protrusion 41 is along the fracture origin 33, the initial stress concentrated on the protrusion 39 is transmitted to the fracture origin 33, causing the fracture-prone portion 28 to begin to tear open early, starting from the fracture origin 33, the opposing portion 23 is divided into upper and lower door portions 29, and rotates up and down from the fracture origin 33 around the hinge portion as an axis, the protrusion 30 opens, and the airbag 11 deploys from the protrusion 30 in front of the occupant, protecting the occupant.

[0035] Therefore, even if the tear origin 33 of the tear portion 28 is positioned off-center with respect to the deployment center P of the airbag 11, the tear portion 28 can be reliably ruptured early, allowing for good deployment of the airbag 11. In particular, when the decorative body 16 is disposed in the center of the facing portion 23, it is preferable to set the tear portion 28 around the position of the decorative body 16 so that the decorative body 16 can be held in place on the door portion 29 even when the facing portion 23 is ruptured from the tear portion 28. However, even if the tear origin 33 of the tear portion 28 is shifted from the deployment center P of the airbag 11 due to such a detour, the provision of the protrusion 39 allows the tear portion 28 to be reliably ruptured.

[0036] Furthermore, since the protrusion 39 is located close to a position corresponding to the outer edge of the decorative body 16, even if the weight of the door section 29 increases due to the position of the decorative body 16, stress is concentrated from the protrusion 39 where the airbag 11 first hits the breaking point 33 near the decorative body 16, allowing the door section 29 to be turned smoothly and the airbag 11 to be deployed smoothly.

[0037] Furthermore, since the rupture starting point 33 is aligned along a position corresponding to the linear portion 26, even if the direction of the surface pressure that the back side of the opposing portion 23 receives from the airbag 11 differs across the linear portion 26 when the airbag 11 is deployed, the force acting on the rupture starting point 33 is less likely to vary, and the deployment of the airbag 11 is less likely to become unstable.

[0038] Furthermore, at least a portion of the protrusion 39 extends from the receiving portion 37 toward the fracture origin portion 33 on the back side of the opposing portion 23, so that the airbag 11 that first hits the protrusion 39 then hits the receiving portion 37 on the back side of the decorative body 16 along the protrusion 39, transmitting the stress. As a result, the initial stress is not concentrated on the receiving portion 37, and the airbag 11 can be deployed more effectively.

[0039] Furthermore, in this embodiment, since the decorative body 16 has the smallest left-right dimension at its lower end, the protrusion 39 extending from the position corresponding to the lower edge of this decorative body 16 is also formed narrow in the left-right direction, making it easier to concentrate stress on the fracture starting point 33.

[0040] Furthermore, under normal use conditions, even when an external force is applied to the cover body 13, for example when the airbag device 6 is pushed toward the rear side to sound the horn device, the protrusion 39 can disperse the stress by abutting against the airbag 11 in the folded state and bracing it, so that even if the cover body 13 of the airbag device 6 is repeatedly pushed in, it is possible to suppress the occurrence of poor appearance such as whitening or wrinkles on the surface of the opposing part 23 of the cover main body part 15 caused by the lifting of the intended rupture part 28, etc.

[0041] In one embodiment, the airbag device 6 is not limited to an airbag device for the driver's seat of a vehicle, but can also be applied to a passenger airbag (PAB) device or the like. [Industrial Applicability]

[0042] The present invention is suitably used as a cover body for an airbag device for the driver's seat of a vehicle such as an automobile. [Explanation of symbols]

[0043] 6 Airbag device 11 Airbag 13 Cover body 15 Cover body 16 Decoration 23 Opposing part 28 Breaking section 29 Door section 33 Break starting point 37 Receiving part 39 Protrusion P development center

Claims

1. a cover main body portion that covers the airbag in a folded state; a decorative body attached to the cover body, The decorative body is located opposite to the deployment center of the airbag, The cover main body portion is a facing portion facing the airbag and having the decorative body located on the front side; a rupture portion formed on the rear side of the facing portion, the rupture portion having a rupture origin portion located at a position offset from the deployment center of the airbag, the rupture portion being ruptured by the deployment pressure of the airbag when the airbag is inflated and deployed, thereby dividing the facing portion into a plurality of door portions; On the back side of the facing portion, there is a protruding portion that is close to a position corresponding to the outer edge of the decorative body and the breaking start point and that protrudes most toward the airbag side. A cover body for an airbag device characterized in that:

2. The cover body has a receiving portion recessed from the front side to the back side of the facing portion to which the decorative body is attached, At least a portion of the protruding portion extends from the receiving portion toward the fracture origin portion on the rear side of the opposing portion.

2. The cover body for an airbag device according to claim 1.

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